Preheat oven to 180°C and lightly spray a doughnut pan with cooking oil.
In a medium size bowl sift flour, baking powder, nutmeg and salt and mix gently with a spatula to combine.
In a large bowl, whisk together egg, sugar and vanilla. Add in oil and whisk until combined. Add in dry ingredients and whisk, slowly add in the dairy-free milk until batter is smooth.
Pour batter into a large piping bag or ziplock bag and cut off the tip. Pipe batter into the doughnut pan ensuring each hole is only half full.
Place in the oven and bake for 8 minutes or until the tops spring back when lightly touched. Let cool in the pan for 2 minutes and turn out onto a wire rack to cool completely.
To make the glaze, add the melted dairy-free butter and icing sugar to a bowl and whisk together. Add in vanilla and 1 tablespoon of the milk and continue whisking. Add more milk until the glaze coats the back of a spoon. Add a few drops of food colouring and mix through.
Dunk the top of each doughnut into the glaze and then place on a wire rack with a piece of baking paper under it to collect any excess glaze that drips off. Decorate each doughnut with sprinkles and set aside until the glaze has set. Store the doughnuts in an airtight container at room temperature for 1-2 days or in the fridge for 3-4 days.